To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
This thesaurus is starting to feel slightly out of date as the language changes, but I still prefer the format by far over others I have browsed in bookstores. I bought my original in high school in 1988 and bought a second copy to have at work. I hope that the copyright holder will someday produce an update.